Command Line Execution through SQL Injection |
Attack Pattern ID: 108 (Standard Attack Pattern Completeness: Complete) | Typical Severity: Very High | Status: Draft |
Summary
An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.
Attack Execution Flow
Probe for SQL Injection vulernability:
The attacker injects SQL syntax into user-controllable data inputs to search unfiltered execution of the SQL syntax in a query.
Indicators
ID type Indicator Description Environments 1 Negative Attacker receives normal response from server.
env-Web env-ClientServer env-Peer2Peer env-CommProtocol2 Positive Attacker receives an error message from server indicating that there was a problem with the SQL query.
env-Web env-ClientServer env-Peer2Peer env-CommProtocol3 Negative Server sends a specific error message that indicates programmatic parsing of the input data (e.g. NumberFormatException)
env-Web env-ClientServer env-Peer2Peer env-CommProtocolOutcomes
ID type Outcome Description 1 Success At least one user-controllable input susceptible to injection found.2 Failure No user-controllable input susceptible to injection found.Security Controls
ID type Security Control Description 1 Detective Search for and alert on unexpected SQL keywords in application logs (e.g. SELECT, DROP, etc.).2 Preventative Input validation of user-controlled data before including it in a SQL query3 Preventative Use parameterized queries (e.g. PreparedStatement in Java, and Command.Parameters.Add() to set query parameters in .NET)
Achieve arbitrary command execution through SQL Injection with the MSSQL_xp_cmdshell directive:
The attacker leverages a SQL Injection attack to inject shell code to be executed by leveraging the xp_cmdshell directive.
Outcomes
ID type Outcome Description 1 Success Attacker's injected code is executed.Security Controls
ID type Security Control Description 1 Preventative Disable xp_cmdshell stored procedure on the database.2 Detective Search for and alert on unexpected SQL keywords in application logs (e.g. SELECT, DROP, etc.).3 Preventative Input validation of user-controlled data before including it in a SQL query4 Preventative Use parameterized queries (e.g. PreparedStatement in Java, and Command.Parameters.Add() to set query parameters in .NET)SecurityDatabase\Alert\Inject malicious data in the database:
Leverage SQL injection to inject data in the database that could later be used to achieve command injection if ever used as a command line argument
Security Controls
ID type Security Control Description 1 Detective Search for and alert on unexpected SQL keywords in application logs (e.g. SELECT, DROP, etc.).2 Preventative Input validation of user-controlled data before including it in a SQL query3 Preventative Use parameterized queries (e.g. PreparedStatement in Java, and Command.Parameters.Add() to set query parameters in .NET)Trigger command line execution with injected arguments:
The attacker causes execution of command line functionality which leverages previously injected database content as arguments.
Outcomes
ID type Outcome Description 1 Success Attacker's injected code is executed.
The application does not properly validate data before storing in the database
Backend application implicitly trusts the data stored in the database
Malicious data is used on the backend as a command line argument
Description
SQL injection vulnerability in Cacti 0.8.6i and earlier, when register_argc_argv is enabled, allows remote attackers to execute arbitrary SQL commands via the (1) second or (2) third arguments to cmd.php. NOTE: this issue can be leveraged to execute arbitrary commands since the SQL query results are later used in the polling_items array and popen function (CVE-2006-6799).
Reference: detail.php?alert=CVE-2006-6799
Skill or Knowledge Level: High
The attacker most likely has to be familiar with the internal functionality of the system to launch this attack. Without that knowledge, there are not many feedback mechanisms to give an attacker the indication of how to perform command injection or whether the attack is succeeding.
Disable MSSQL xp_cmdshell directive on the database
Properly validate the data (syntactically and semantically) before writing it to the database.
Do not implicitly trust the data stored in the database. Re-validate it prior to usage to make sure that it is safe to use in a given context (e.g. as a command line argument).
- Data Modification
- Information Leakage
- Denial of Service
- Privilege Escalation
- Run Arbitrary Code
CWE-ID | Weakness Name | Weakness Relationship Type |
---|---|---|
89 | Improper Sanitization of Special Elements used in an SQL Command ('SQL Injection') | Targeted |
74 | Failure to Sanitize Data into a Different Plane ('Injection') | Secondary |
20 | Improper Input Validation | Secondary |
78 | Improper Sanitization of Special Elements used in an OS Command ('OS Command Injection') | Targeted |
114 | Process Control | Targeted |
Nature | Type | ID | Name | Description | View(s) this relationship pertains to |
---|---|---|---|---|---|
ChildOf | Attack Pattern | 248 | Command Injection | Mechanism of Attack (primary)1000 |
Validate all data syntactically and semantically before writing it to the database
Do not implicitly trust database data and validate it to ensure that it is safe in the context in which it is being used